When connecting pipes in a motor vehicle together, for example, a flexible hose is placed on an outer circumference of an end portion of a pipe, and an outer circumference of the hose is fastened by a hose clamp, thereby fixing the hose to the pipe.
For example, Patent Literature 1 discloses a hose clamp including a C-shaped plate spring main body (a fastening ring 1) and a pair of grip pieces (one grip 2A and the other grip 2B) which are erected from both end portions of the plate spring main body in a radial direction so as to intersect each other. One grip piece is formed into an arch-shaped wide dimension in which a guide groove is opened, while the other grip piece is formed into a narrow dimension to be movable within the guide groove. When the plate spring main body is in the free state, the plate spring main body is diametrically contracted for fastening the hose. And, by bringing both the grip pieces close to each other, the plate spring main body is diametrically expanded. On the one grip piece, a hook-shaped locking portion (a locking portion 4) for engaging with the other grip piece and a taper portion (a guide portion 5) for guiding the other grip piece when it is disengaged from the locking portion are formed.
By bringing both the grip pieces close to each other in a circumferential direction with a tool such as a pair of pliers, the locking portion of the one grip piece is engaged with the other grip piece, whereby the plate spring main body is held in the diametrically expanded state. The hose clamp in this state is disposed on an outer circumference of a hose. Then, by bringing both the grip pieces further close to each other, the other grip piece is guided by the taper portion to move in a width direction to a position where the other gripping portion is not to be engaged with the locking portion again. By opening the tool in this state, the plate spring main body restores elastically, whereby the hose is fastened and fixed.